Generally, there is a range of guaranteed operating temperature for electric devices, and it is possible that electric devices do not operate normally in environments out of the range. For example, in the case of electric devices with the guaranteed operating temperature from −5° C. to 40° C., continuous utilization in a high-temperature range over 40° C. for a long time may result in faulty or malfunction. Further, when starting up the electric devices at low-temperatures below −5° C., problems such as damage or deterioration of the components are likely to occur due to rapid change in temperature right after the startup.
Therefore, electric devices are provided with a cooling mechanism such as cooling fans and the like as a measure against high temperature. Further, as a measure against low temperature, there are electric devices equipped with a mechanism for preventing rapid temperature rise right after the startup.
For example, the electric device disclosed in JP 2004-185439A (Patent Document 1) has a cooling fan and a fan control device with a temperature sensor as the measure against high temperature. The fan control device with a temperature sensor adjusts the temperature inside the device by controlling the starting and stopping of the cooling fan according to the temperature change inside the device. Further, as the measure against low temperature, when started up at a low temperature below a predetermined startup temperature, the CPU constituting the main unit of the electric device (server devices and the like) keeps the BIOS operating state without executing the OS, and carries out a warm-up operation. During the warm-up operation, the cooling fan is stopped. During the warm-up operation, the temperature inside the device rises due to the heat emitted by the main unit of the device and, when it reaches the startup temperature, the CPU executes the OS, and subsequently executes application programs.
Because the electric device disclosed in JP 2004-185439A (Patent Document 1) utilizes the heat emitted by the main unit of the electric device to carry out the warm-up operation, it does not need a heat source such as a heater and the like as the measure against low temperature. However, the cooling fan for the measure against high temperature is stopped during the warm-up operation. This is because it is conceivable that if the cooling fan is rotated during the warm-up operation, then the air inside the device (to be referred to as the inner air) warmed at last may be exchanged with the air outside the device (to be referred to as the outer air) so as to hinder the temperature rise inside the device. However, this phenomenon occurs when the outer air is lower in temperature than the inner air, but does not occur when the outer air is higher in temperature than the inner air. On the contrary, if the outer air is hotter than the inner air, then it is possible to facilitate temperature rise inside the electric device by introducing the outer air.